Locking Fuel Cap

Im needing to fit a locking fuel cap to my 1985 defender, and I cant seem to find one to fit, as its the old style wide one,
The only option I can come up with is to replace the filler neck & hose to the tank, I think it looks a straight forward swap.
any one done this before? i cant be the first lol

I asked the same thing a few weeks back - also have a 1985 County with the wide filler. The concensus was two options - padlock or replace the filler tube with a narrow one. I havent done it yet as my landy lives in a garage and I live in a low crime area!

Its on the list though.